Defect inspection device, defect inspection method, method for producing separator roll, and separator roll

ABSTRACT

To inspect a separator roll for a defect inside the separator roll with use of only a small number of defect inspection devices, a defect inspection device (1) includes: a radiation source section (2) configured to emit an electromagnetic wave (4) to a separator roll (10); and a sensor section (3) configured to detect the electromagnetic wave (4) having passed through the separator roll (10).

This Nonprovisional application claims priority under 35 U.S.C. § 119 onPatent Applications No. 2017-129780 filed in Japan on Jun. 30, 2017, andNo. 2016-233578 filed in Japan on Nov. 30, 2016, the entire contents ofwhich are hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to (i) a device for inspecting a separatorroll for a defect, (ii) a method for inspecting a separator roll for adefect, (iii) a method for producing a separator roll, and (iv) aseparator roll.

BACKGROUND ART

A lithium-ion secondary battery includes a cathode and an anode that areseparated by a porous separator. Lithium-ion secondary batteries areproduced with use of a separator roll, which includes a cylindrical coreand the above separator wound around the core. A separator roll may havea defect as a result of, for example, trapping a foreign object insidethe separator during the production. This necessitates inspecting theseparator for a defect. In a case where in particular, a separator has adefect caused by an electrically conductive foreign object such asmetal, the foreign object may cause a short circuit inside thelithium-ion secondary battery.

Patent Literature 1 discloses a defect inspection device configured to(i) emit visible light and infrared light to a surface of a sheet beingconveyed and (ii) on the basis of data on an image captured incorrespondence with the amount of each of the visible light and theinfrared light reflected, determine whether a defect on the surface ofthe sheet is caused by metal.

CITATION LIST Patent Literature

-   [Patent Literature 1]-   Japanese Patent No. 5673621

SUMMARY OF INVENTION Technical Problem

Separator rolls are produced by (i) slitting a single separator originalsheet into a plurality of separators in accordance with the size oflithium-ion secondary batteries to be produced and (ii) winding eachseparator around a core.

When a separator original sheet is slit, a metal foreign object tends toresult from a metal blade. It is thus preferable to inspect slitseparators for a defect.

If, however, the defect inspection device disclosed in Patent Literature1 is used to inspect, for a defect, a surface of a sheet-shapedseparator after the slitting and before it is wound around a core, therewill be a need for the same number of defect inspection devices as thenumber of separators produced by slitting an original sheet. This willincrease the cost of producing separator rolls.

Since a metal foreign object results also from, for example, a slidingsection of a transfer roller, it is preferable to inspect a separatorfor a defect after it is wound around a core into a separator roll(after this step, the separator will not come into contact with aroller). The defect inspection device disclosed in Patent Literature 1is unfortunately incapable of, once a separator has been wound around acore, inspecting the separator for any foreign object trapped inside theseparator.

The present invention has been accomplished in view of the above issue.It is an object of the present invention to inspect a separator roll fora defect inside the separator roll with use of only a few defectinspection devices.

Solution to Problem

In order to attain the above object, a defect inspection device inaccordance with an embodiment of the present invention includes: aradiation source section configured to emit an electromagnetic wave to aseparator roll including (i) a core in a cylindrical shape and (ii) aseparator for use in a battery which separator is wound around the core,the electromagnetic wave being capable of passing through the separatorroll; and a sensor section configured to detect the electromagnetic wavehaving been emitted by the radiation source section and passed throughthe separator roll.

In order to attain the above object, a defect inspection method inaccordance with an embodiment of the present invention includes thesteps of: causing a radiation source section to emit an electromagneticwave to a separator roll including (i) a core in a cylindrical shape and(ii) a separator for use in a battery which separator is wound aroundthe core, the electromagnetic wave being capable of passing through theseparator roll; and detecting the electromagnetic wave having passedthrough the separator roll.

In order to attain the above object, a separator roll in accordance withan embodiment of the present invention includes: a core in a cylindricalshape; and a separator for use in a battery which separator is woundaround the core, the separator roll containing, inside the separator, noforeign object that is not less than 100 μm.

Advantageous Effects of Invention

An embodiment of the present invention advantageously makes it possibleto inspect a separator roll for a defect inside the separator roll withuse of only a small number of defect inspection devices.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 provides diagrams schematically illustrating the configuration ofa slitting apparatus in accordance with Embodiment 1 of the presentinvention.

FIG. 2 shows diagrams each schematically illustrating the configurationof a separator roll in accordance with Embodiment 1 of the presentinvention, where (a) illustrates a separator that has not been wound offfrom a core, (b) illustrates a separator that has been wound off from acore, (c) illustrates a core from which a separator has been wound offand removed, and (d) illustrates the separator of (b) from a differentangle.

FIG. 3 is a diagram schematically illustrating the configuration of adefect inspection device in accordance with Embodiment 1 of the presentinvention.

FIG. 4 is a diagram illustrating a captured image of a separator rollheld by a holding mechanism of a defect inspection device in accordancewith Embodiment 1 of the present invention.

FIG. 5 is a diagram illustrating the separator roll of FIG. 4 as hasbeen rotated in the θ direction by a predetermined angle.

FIG. 6 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 1 of the present invention.

FIG. 7 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 2 of the present invention.

FIG. 8 is a diagram schematically illustrating the configuration of adefect inspection device in accordance with Embodiment 3 of the presentinvention.

FIG. 9 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 3 of the present invention.

FIG. 10 is a diagram schematically illustrating the configuration of adefect inspection device in accordance with Embodiment 4 of the presentinvention.

FIG. 11 is a diagram illustrating a captured image of a separator rollheld by a holding mechanism of a defect inspection device in accordancewith Embodiment 4 of the present invention.

FIG. 12 is a diagram illustrating the separator roll of FIG. 11 as hasbeen moved in the Y-axis direction and the Z-axis direction over apredetermined distance.

FIG. 13 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 4 of the present invention.

FIG. 14 is a diagram schematically illustrating the configuration of aradiation source section in accordance with Embodiment 1 of the presentinvention.

FIG. 15 is a diagram illustrating how a defect inspection device inaccordance with Embodiment 1 of the present invention carries out ameasurement at a high magnification and at a low magnification.

FIG. 16 is a diagram schematically illustrating the configuration of adefect inspection device in accordance with Embodiment 5 of the presentinvention.

FIG. 17 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 6 of the present invention.

FIG. 18 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 7 of the present invention.

FIG. 19 is a diagram schematically illustrating the configuration of adefect inspection device in accordance with Embodiment 8 of the presentinvention.

FIG. 20 is a diagram illustrating a captured image of a separator rollheld by a holding mechanism of Embodiment 8 of the present invention.

FIG. 21 is a diagram illustrating the separator roll of FIG. 20 as hasbeen rotated by an angle 30.

FIG. 22 is a diagram illustrating the configuration of a defectinspection device in accordance with Embodiment 9 of the presentinvention.

FIG. 23 is a diagram illustrating the configuration of a defectinspection device in accordance with a modification of Embodiment 9 ofthe present invention.

FIG. 24 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 9 of the present invention.

FIG. 25 is a diagram illustrating the configuration of a defectinspection device in accordance with a modification of Embodiment 1 ofthe present invention.

DESCRIPTION OF EMBODIMENTS Embodiment 1

(Process of Producing Separator Roll)

With reference to FIG. 1, the description below first deals with aprocess of producing a separator roll in accordance with Embodiment 1 ofthe present invention.

FIG. 1 provides diagrams schematically illustrating a configuration of aslitting apparatus 6 configured to slit a separator original sheet. (a)of FIG. 1 illustrates the entire configuration, and (b) of FIG. 1illustrates an arrangement before and after slitting a separatororiginal sheet.

While separating the cathode (which is the positive electrode of alithium-ion secondary battery or the like) and the anode, the separator12, which is a porous film, allows lithium ions to move between thecathode and the anode. The separator 12 contains, for example, apolyolefin (for example, polyethylene or polypropylene) as a materialthereof.

The separator 12 may include a porous film and a heat-resistant layer ona surface of the porous film to have heat resistance. The heat-resistantlayer may contain, for example, wholly aromatic polyamide (aramid resin)as a material thereof.

The separator 12 may be a layered porous film including (i) a porousfilm containing a polyolefin and (ii) a functional layer(s) such as anadhesive layer and a heat-resistant layer. The functional layer containsresin. Examples of the resin include: a polyolefin such as polyethyleneor polypropylene; a fluorine-containing polymer such as polyvinylidenefluoride (PVDF), polytetrafluoroethylene, or a vinylidenefluoride-hexafluoropropylene copolymer; an aromatic polyamide; a rubbersuch as a styrene-butadiene copolymer and a hydride thereof, amethacrylate ester copolymer, an acrylonitrile-acrylic ester copolymer,or a styrene-acrylic ester copolymer; a polymer having a melting pointor glass transition temperature of not lower than 180° C.; and awater-soluble polymer such as polyvinyl alcohol, polyethylene glycol,cellulose ether, sodium alginate, polyacrylic acid, polyacrylamide, orpolymethacrylic acid. The functional layer may contain a filler made ofan inorganic substance or organic substance. The inorganic filler ismade of, for example, an inorganic oxide such as silica, magnesiumoxide, alumina, aluminum hydroxide, or boehmite. Alumina has crystalforms such as α-alumina, β-alumina, γ-alumina, and θ-alumina, and any ofthe crystal forms may be used. The resin and the filler may each contain(i) only one kind or (ii) two or more kinds in combination. In a casewhere the functional layer contains a filler, the filler may becontained in an amount of not less than 1% by volume and not more than99% by volume of the functional layer.

The separator 12 should desirably contain as small an amount of water aspossible for a minimized influence on the defect inspection describedlater. The defect inspection during the defect inspection step describedlater involves causing an electromagnetic wave such as X rays to passthrough a separator 12 in order to inspect the separator 12, woundaround a core, for a foreign object inside the separator 12. Since waterdecreases the transmittance of an electromagnetic wave such as X rays,the separator 12 containing a large amount of water will undesirablydecrease the accuracy of the defect inspection.

The separator 12 may contain water in an amount of preferably up toapproximately 2000 ppm. This makes it possible to (i) prevent a decreasein the transmittance of an electromagnetic wave such as X rays and (ii)accurately inspect a separator wound around a core for a defect insidethe separator during the defect inspection step described later.

The separator 12 may preferably have a width (hereinafter referred to as“product width”) suitable for an application product such as alithium-ion secondary battery. For an improved productivity, however, aseparator is first produced to have a width that is equal to or largerthan the product width. Then, after having been produced to have a widthequal to or larger than the product width, the separator is slit to havethe product width.

The expression “width of a/the separator” refers to that dimension ofthe separator which extends in a direction substantially perpendicularto the longitudinal direction of the separator and to the thicknessdirection of the separator. The description below uses the term“original sheet” to refer to a wide separator that has not been slit.Further, expressions such as “slitting” mean making a slit in aseparator original sheet in the longitudinal direction (that is, thedirection [carrying direction] in which the film is transferred duringthe production; machine direction [MD]), and expressions such as“cutting” mean cutting a separator original sheet in the transversedirection (TD). The transverse direction (TD) refers to a direction thatis substantially perpendicular to the longitudinal direction (MD) of theseparator and to the thickness direction of the separator.

The slitting apparatus 6 is configured to slit an original sheet. Theslitting apparatus 6 includes a rotatably supported cylindrical wind-offroller 61, rollers 62 to 69, and wind-up rollers 70U and 70L.

In the slitting apparatus 6, a cylindrical core c around which anoriginal sheet is wound is fit on the wind-off roller 61.

The original sheet is wound off from the core c to a route U or L. Theoriginal sheet having been wound off is conveyed to the roller 68 viathe rollers 62 to 67. During the step of conveying the original sheetfrom the roller 67 to the roller 68, the original sheet is slit into aplurality of separators (slitting step). The slitting apparatus 6includes a slitting device (not shown in FIG. 1) disposed near theroller 68 and configured to slit an original sheet into a plurality ofseparators.

After the slitting step, some of the separators produced by slitting theoriginal sheet are each wound around a cylindrical core u (bobbin) fiton the wind-up roller 70U, whereas the other of the separators are eachwound around a cylindrical core 1 (bobbin) fit on the wind-up roller 70L(separator winding step).

The present specification uses the term “separator roll” to refer tothat which includes (i) a separator produced by slitting an originalsheet and (ii) a core (bobbin) around which the separator is wound inthe shape of a roll. The present embodiment is configured to, after aseparator roll has been produced through the separator winding step,inspect the separator roll for any foreign object inside the separator(wound around the core) during the defect inspection step describedlater. During the slitting step described above, a foreign object tendsto result from, for instance, a metal slitting blade being chipped andthe resulting piece adhering to a surface of a slit separator. Thedefect inspection step may thus preferably be carried out after theslitting step. This makes it possible to efficiently inspect, during thedefect inspection step, a separator for any foreign object resultingfrom the slitting step, during which a foreign object tends to result.

Separator rolls that have been determined as non-defective during thedefect inspection step are later packed together in a package during apackaging step for storage.

The separator 12 produced by slitting an original sheet during theslitting step and wound around a core may preferably have a width (thatis, the dimension in the TD) of, for example, approximately not lessthan 30 mm and not more than 100 mm. If the separator 12 has anexcessively large width, an electromagnetic wave such as X rays will noteasily pass through the separator 12 for the defect inspection duringthe defect inspection step described later, with the result of adecrease in the accuracy of the defect inspection. In view of that, theseparator 12 having a width of approximately not more than 100 mm makesit possible to (i) prevent a decrease in the transmittance of anelectromagnetic wave such as X rays and (ii) accurately inspect aseparator wound around a core for a defect inside the separator duringthe defect inspection step described later.

(Configuration of Separator Roll)

FIG. 2 shows diagrams each schematically illustrating the configurationof a separator roll 10 in accordance with Embodiment 1 of the presentinvention. (a) of FIG. 2 illustrates a separator 12 that has not beenwound off from a core 8. (b) of FIG. 2 illustrates a separator 12 thathas been wound off from a core 8. (c) of FIG. 2 illustrates a core fromwhich a separator 12 has been wound off and removed. (d) of FIG. 2illustrates the separator 12 of (b) of FIG. 2 from a different angle.

As illustrated in FIG. 2, a separator roll 10 includes a core 8 and aseparator 12 wound around the core 8. The separator 12 has been producedby slitting an original sheet as described above. The presentspecification uses the term “outer peripheral surface S1” to refer to,among a plurality of surfaces of a separator roll 10, the outerperipheral surface of the separator 12 wound in the shape of a roll.

The core 8 includes an outer cylindrical part 81, an inner cylindricalpart 82, and a plurality of ribs 83. The core 8 is identical to thecores u and l mentioned above.

The outer cylindrical part 81 is a cylindrical member around which aseparator 12 is to be wound to be in contact with the outer peripheralsurface S2 of the outer cylindrical part 81. The inner cylindrical part82 is a cylindrical member having a central hole 8 a in which a wind-uproller or the like is to be fit to be in contact with the innerperipheral surface of the inner cylindrical part 82. The ribs 83 aresupport members that (i) extend from the outer peripheral surface of theinner cylindrical part 82 to the inner peripheral surface of the outercylindrical part 81 and that (ii) support the outer cylindrical part 81from the side of its inner peripheral surface.

The core 8 contains ABS resin as a material thereof. The material of thecore 8 in accordance with Embodiment 1 of the present invention is,however, not limited to ABS resin. The core 8 may contain, as a materialthereof, a resin other than ABS resin such as polyethylene resin,polypropylene resin, polystyrene resin, or vinyl chloride resin. Thecore 8 should preferably not contain metal, paper, or fluorocarbon resinas a material thereof.

As illustrated in (b) and (d) of FIG. 2, the separator 12 has an endattached to the core 8 with adhesive tape 130. Specifically, theseparator 12 has an end fixed to the outer peripheral surface S2 of thecore 8 with use of adhesive tape 130 provided with an adhesive. An endof the separator 12 may be fixed to the outer peripheral surface S2 by,instead of using adhesive tape 130, applying an adhesive directly to anend of the separator 12, using a clip, or the like method.

(Configuration of Defect Inspection Device 1)

FIG. 3 is a diagram schematically illustrating the configuration of adefect inspection device 1 in accordance with Embodiment 1 of thepresent invention. The defect inspection device 1 is configured toinspect a separator roll for a defect during the defect inspection step.The present embodiment assumes that the defect inspection device 1 isconfigured to inspect a wound separator 12 for any foreign object insidethe separator 12.

The defect inspection device 1 includes (i) a radiation source section 2configured to emit an electromagnetic wave 4, (ii) a sensor section 3configured to detect the electromagnetic wave 4 emitted by the radiationsource section 2, and (iii) a holding mechanism 20 configured to hold aseparator roll 10. The defect inspection device 1 further includes acontrol section 30 configured to control driving of the entire defectinspection device 1 which driving includes driving of the radiationsource section 2, driving of the sensor section 3, and driving of theholding mechanism 20.

The control section 30 includes (i) a radiation source control section31 configured to control driving of the radiation source section 2, (ii)a holding mechanism control section 32 configured to control driving ofthe holding mechanism 20, and (iii) a sensor control section 33configured to control driving of the sensor section 3 and obtaining acaptured image based on detection information from the sensor section 3.

The defect inspection device 1 is configured such that at least theradiation source section 2, the holding mechanism 20, and the sensorsection 3 are surrounded by a wall (not shown in FIG. 3) containing, forexample, lead to prevent an electromagnetic wave from passingtherethrough easily so that the electromagnetic wave used does not leakoutward. The wall may surround at least the radiation source section 2,the sensor section 3, and the holding mechanism 20.

The present embodiment is configured such that the radiation sourcesection 2 emits an electromagnetic wave 4 in the X-axis direction (thatis, the left-right direction of FIG. 3) and that the vertical direction(that is, the up-down direction of FIG. 3), which is perpendicular tothe X axis, corresponds to the Z-axis direction.

The holding mechanism 20 is configured to hold a separator roll 10 as aninspection target in such a manner as to be capable of moving theseparator roll 10 in the X-axis direction and the Z-axis direction. Theholding mechanism 20, in other words, moves the separator roll 10relative to the radiation source section 2. The holding mechanism 20 maybe configured to be capable of moving the separator roll 10 also in theY-axis direction (that is, the direction perpendicular to the surface ofFIG. 3), which is perpendicular to the X-axis direction and the Z-axisdirection.

The holding mechanism 20 is shaped to extend in the X-axis direction.The forward end of the holding mechanism 20 is inserted in the centralhole 8 a of a separator roll 10 so that the separator roll 10 issupported by the holding mechanism 20. With this configuration, theseparator roll 10 is set in such a manner that in the defect inspectiondevice 1, at least a portion of the separator 12 wound around the core 8is present between the radiation source section 2 and the sensor section3.

The holding mechanism 20 may, for prevention of generation of a metalforeign object, preferably be configured such that at least its slidingsection is made of resin. The resin is not limited to any kind. Examplesof the resin include: a general-purpose resin such as polyethyleneresin, polypropylene resin, polystyrene resin, vinyl chloride resin,acrylic resin, ABS, or polyester; an engineering plastic such aspolyacetal, polyamide, polycarbonate, or modified polyphenylene ether;and a super engineering plastic such as polyalylate, polysulfone,polyether sulfone, polyphenylene sulfide, polyether ether ketone,polyimide, or polyetherimide. As the resin is for use in the slidingsection, the resin may preferably be, among the above resins, anabrasion-resistant super engineering plastic, more preferably polyetherether ketone. Embodiment 3 described later of the present invention maypreferably be configured such that the holding mechanism 20 is entirelymade of resin.

A separator roll 10 may be fitted on the holding mechanism 20 by, forexample, (i) moving a separator roll 10, with use of a robot arm ormanually, from a place such as a rack or conveyor belt on whichseparator rolls 10 that have not been subjected to defect inspection areplaced and (ii) fitting the separator roll 10 on the holding mechanism20 so that the forward end of the holding mechanism 20 is insertedthrough the separator roll 10.

A separator roll 10 may be removed from the holding mechanism 20 holdingthe separator roll 10 by, for example, removing, with use of a robot armor manually, the separator roll 10 that has been subjected to defectinspection. The separator roll 10, which has been removed from theholding mechanism 20, is placed on, for example, a rack or conveyorbelt.

A robot arm may have the function of the holding mechanism 20. Such aconfiguration in which a robot arm has the function of the holdingmechanism 20 will be described later with reference to FIG. 25.

With a separator roll 10 set on the holding mechanism 20, the defectinspection device 1 is configured such that the radiation source section2, the separator roll 10, and the sensor section 3 are arranged in thisorder in the X-axis direction. The separator roll 10 set on the holdingmechanism 20 has opposite side surfaces, one of which faces the emittingsurface 2 a of the radiation source section 2 and the other of whichfaces the detecting surface 3 a of the sensor section 3. The presentspecification uses (i) the term “first side surface A1” to refer to thatside surface of the separator roll 10 which is close to the radiationsource section 2 and (ii) the term “second side surface A2” to refer tothat side surface of the separator roll 10 which is close to the sensorsection 3.

The defect inspection device 1 in accordance with the present embodimentis configured to repeat the operation of (i) rotating the separator roll10, which is held by the holding mechanism 20, in the θ direction by apredetermined angle and (ii) capturing an image of the separator roll 10in order to capture an image of the entire separator 12 wound around thecore 8 in the shape of a ring. This image capturing will be describedlater in detail with reference to, for example, FIG. 4.

As illustrated in FIG. 3, the sensor section 3 is a detector capable ofdetecting, at the detecting surface 3 a, the electromagnetic waveemitted by the radiation source section 2. The sensor section 3, when ithas detected the electromagnetic wave emitted by the radiation sourcesection 2, outputs to the sensor control section 33 an electric signalcorresponding to the intensity of the electromagnetic wave detected. Thesensor control section 33, when it has received such electric signalsfrom the sensor section 3, generates a captured image on the basis ofthose electric signals.

The radiation source section 2 may be an X ray source, a γ ray source,or an equivalent high-energy electromagnetic radiation source. Thesensor section 3 is a detector capable of detecting an electromagneticwave having a wavelength range identical to the wavelength range of theelectromagnetic wave that the radiation source section 2 emits. Forinstance, in a case where the radiation source section 2 is configuredto emit X rays, the sensor section 3 is a detector capable of detectingX rays, such as a flat-panel detector, a charge coupled device (CCD)area image sensor, a complementary metal oxide semiconductor (CMOS) areaimage sensor, or equivalents thereto, and in a case where the radiationsource section 2 is configured to emit γ rays, the sensor section 3 is adetector capable of detecting γ rays, such as an amorphous silicon thinfilm transistor (TFT) flat-panel detector, or equivalents thereto.

The present embodiment is configured such that the sensor section 3 iscapable of detecting X rays and is a flat-panel detector (FPD) includingpixels arranged in a matrix. The sensor section 3 is a FPD including,for example, pixels arranged in a matrix of 1500×1500 or 2000×2000 whichpixels each have a size (for example, 20 μm to 2000 μm) suitable for thesize of a foreign object as a detection target.

The sensor section 3 may have a detecting surface 3 a having an areasmaller than the area of the corresponding side surface of the separatorroll 10. This is because the present embodiment is configured to createa captured image of the entire separator roll 10 by (i) repeating theoperation of rotating the separator roll 10 and capturing an image of aportion of the separator 12 wound around the core 8 in multiple layersin the shape of a ring, (ii) extracting necessary regions from thosecaptured images, and (iii) connecting the necessary regions.

The radiation source section 2 of the present embodiment is configuredto emit an electromagnetic wave 4 that passes, in the transversedirection (TD), through the separator 12 of a separator roll 10 whichseparator 12 has a width W. Examples of such an electromagnetic wave 4include an electromagnetic wave having a wavelength within a range of 1μm to 10 nm.

The electromagnetic wave 4, which the radiation source section 2 emits,may preferably be X rays among others. This makes it possible to producea defect inspection device that is inexpensive and easy to use, ascompared to a case in which the radiation source section 2 emits γ raysas the electromagnetic wave 4.

The electromagnetic wave 4, which the radiation source section 2 emits,may preferably have an intensity of not less than 1 W. This ensures thatthe electromagnetic wave 4 passes through a separator 12 in thetransverse direction (TD). If the electromagnetic wave 4 has a lowintensity, the exposure time period will need to be long. In view ofthat, the electromagnetic wave 4, which the radiation source section 2emits, may more preferably have an intensity of not less than 10 W. Thisallows the exposure time period to be short.

If the electromagnetic wave 4 has too high an intensity, the radiationsource section 2 may have a short life. In view of that, theelectromagnetic wave 4, which the radiation source section 2 emits, maypreferably have an intensity of not more than 100 W. This prevents theradiation source section 2 from having a short life.

The emitting surface 2 a of the radiation source section 2, from whichemitting surface 2 a the radiation source section 2 emits theelectromagnetic wave 4, faces the detecting surface 3 a of the sensorsection 3 with a separator roll 10 therebetween that has been set in thedefect inspection device 1.

In a case where the electromagnetic wave 4 of the present embodiment hasa wavelength within a range of 1 μm to 10 nm, the present specificationmay use the particular term “focus 2 c” to refer to the point source ofthe radiation source section 2 which point source is for emitting theelectromagnetic wave 4 radially. The focus 2 c has a center 2 d thatcoincides with the center 2 b of the emitting surface 2 a as viewed inthe X-axis direction.

FIG. 14 is a diagram schematically illustrating the configuration of aradiation source section 2 in accordance with Embodiment 1 of thepresent invention. The radiation source section 2 may ideally have apoint light source. The focus 2 c typically has a diameter 2 ca within arange of approximately 1 μm to 20 μm.

The present embodiment assumes that a separator roll 10 has oppositeside surfaces, one of which is a first surface A1 facing the radiationsource section 2 and the other of which is a second surface A2 facingthe sensor section 3, as illustrated in FIGS. 3 and 15. The presentembodiment also assumes that (i) the focus 2 c and the second surface A2of the separator roll 10 are separated from each other by a distance D1and that (ii) the focus 2 c and the detecting surface 3 a of the sensorsection 3 are separated from each other by a distance D2.

As illustrated in FIG. 15, in a case where the defect inspection device1 carries out a measurement at a high magnification, there will be alarge influence of displacement due to the size of the focus 2 c. Thecase of carrying out a measurement at a high magnification means a caseof carrying out a measurement in which D2(D2/D1) is large relative toD1, whereas the case of carrying out a measurement at a lowmagnification means a case of carrying out a measurement in which D2(D2/D1) is small relative to D1.

As illustrated in FIG. 3, the radiation source section 2 emits anelectromagnetic wave 4 toward a side surface of a separator roll 10.Assuming that the separator 12 of the separator roll 10 has a width W inthe transverse direction (TD), the radiation source section 2, inresponse to an instruction from the radiation source control section 31,emits an electromagnetic wave 4 having an intensity that allows theelectromagnetic wave 4 to pass through the width W of the separator 12.

The sensor section 3 detects the electromagnetic wave 4, which has beenemitted by the radiation source section 2 and has passed through theseparator roll 10. This configuration makes it possible to inspect aseparator roll 10 for a defect inside the separator roll 10 such as aforeign object inside the separator roll 10.

As described above, the defect inspection device 1 is capable of, aftera separator roll 10 has been produced (that is, after a separator 12 hasbeen wound around a core), inspecting the separator 12 around a core fora defect inside the separator 12. This eliminates the need to prepare adefect inspection device for each of a plurality of sheet-shapedseparators produced by slitting an original sheet during the slittingstep. This in turn eliminates the need to prepare a large number ofdefect inspection devices.

The radiation source section 2 emits an electromagnetic wave 4 to aseparator roll 10 held by the holding mechanism 20, and the sensorsection 3 detects that electromagnetic wave 4. This configurationeliminates the need to capture an image of a separator 12 beingconveyed, thereby making it possible to capture an image of a separatorroll 10 at rest. This in turn ensures a sufficient exposure time period,thereby making it possible to capture a clear image for accurate defectinspection.

While the exposure time period may preferably be long for an improvedsignal-to-noise ratio (SN ratio), the exposure may be a continuousexposure operation or include a plurality of repeated short-timeexposure operations. In a case where the defect inspection device 1 hascaptured images through a plurality of repeated short-time exposureoperations, the defect inspection device 1 then superimposes each imageover the others. Carrying out such a plurality of exposure operations ispreferable because it reduces noise over continuous exposure.

The defect inspection device 1 does not need to capture an image of thefull length of a separator 12 being conveyed, and is capable ofinspecting a separator roll 10 as a wound product. This makes itpossible to carry out defect inspection within a short time.

In a case where the defect inspection involves use of a high-energyelectromagnetic wave such as X rays or γ rays, a radiation source and asensor need to be surrounded by a wall containing, for example, lead forprevention of influence on the human body. If such a configuration is tobe used to carry out defect inspection through emission of X rays to aseparator or separator roll being conveyed, the surrounding wall willneed to be large, with the unfortunate result of a large device.

In contrast, the defect inspection device 1, which is configured tocapture an image of a separator roll 10 held by the holding mechanism20, can include a relatively small wall around the radiation sourcesection 2 and the sensor section 3 in a case where the defect inspectiondevice 1 uses X rays or γ rays as the electromagnetic wave 4. As aresult, the defect inspection device 1 can be relatively small as awhole.

The radiation source section 2 emits an electromagnetic wave 4 to aseparator roll 10 from the side of a side surface of the separator roll10. This configuration makes it possible to create a captured imagebased on an electromagnetic wave 4 that has passed through, of theentire separator roll 10, only the separator 12 wound around a core 8.This in turn makes it possible to create a particularly clear capturedimage of the inside of a separator 12 wound around a core 8.

The radiation source section 2 is configured to emit an electromagneticwave 4 to a separator roll 10 in such a manner that the electromagneticwave 4 strikes not only the separator 12 wound around a core 8 but alsothe core 8. The image captured by the sensor section 3 detecting anelectromagnetic wave 4 a may preferably include not only an image of theseparator 12 but also an image of the core 8. The defect inspectiondevice 1 is capable of creating a captured image of a wide area of aseparator roll 10 as described above. This configuration makes itpossible to reduce the number of image-capturing operations necessaryand inspect the entire separator roll 10 thoroughly for a defect.

In a case where the defect inspection device 1 uses X rays or γ rays asthe electromagnetic wave 4, the radiation source section 2 emits theelectromagnetic wave 4 from the focus 2 c radially with an angle B0.Thus, that electromagnetic wave 4 which has been emitted from the center2 b of the emitting surface 2 a of the radiation source section 2 (thatis, that electromagnetic wave 4 which has been emitted from the focus 2c in a direction perpendicular to the emitting surface 2 a) travelsthrough a separator roll in a direction parallel to the film surface ofthe separator 12 wound around a core 8 and strikes the detecting surface3 a of the sensor section 3 in a direction perpendicular to thedetecting surface 3 a. That electromagnetic wave 4 which has beenemitted from a position apart from the center 2 b of the emittingsurface 2 a of the radiation source section 2 (that is, thatelectromagnetic wave 4 which has been emitted from the focus 2 c in adirection inclined from the electromagnetic wave 4 that has been emittedin a direction perpendicular to the emitting surface 2 a) travelsthrough a separator roll 10 in an accordingly oblique direction relativeto the film surface of the separator 12 wound around a core 8 andstrikes the detecting surface 3 a of the sensor section 3 in anaccordingly oblique direction relative to the detecting surface 3 a.

An emission line may show in that region of a captured image of a woundseparator 12 which has been obtained on the basis of an electromagneticwave 4 that has traveled through the wound separator 12 in a directionparallel to the film surface of the separator 12, as compared to thatregion of the captured image which has been obtained on the basis of anelectromagnetic wave 4 that has traveled through the wound separator 12in an oblique direction relative to the film surface of the separator12. The emission line renders less visible an image of a defect causedby, for example, a foreign object inside a wound separator 12, and mayresult in a false negative in defect detection. In a case where acaptured image shows an emission line, a false negative in defectdetection may be prevented by (i) changing the positional relationshipbetween the radiation source section 2 and the separator 12 and (ii)capturing an image again of that portion in which the emission line isobserved.

Specifically, after an image has been captured of an outer peripheralregion of a separator 12, an image is captured again of that innerperipheral region of the separator 12 which coincides with that outerperipheral region in which an emission line shows. This makes itpossible to inspect a separator 12 for a defect without a false negativein defect detection even in a case where an emission line shows in anouter peripheral region of the separator 12. Further, capturing aplurality of images of overlapping regions while changing the positionalrelationship between the radiation source section 2 and a separator 12as described above makes it possible to prevent a false negative indetecting a flat, thin foreign object among foreign objects each havinga circumscribed sphere with a diameter of not less than 100 μm.

In terms of prevention of an emission line, the radiation source section2 may preferably have an emitting surface 2 a whose center 2 b is sopositioned as not to face that portion of the corresponding side surfaceof a separator roll 10 held by the holding mechanism 20 which is not thewound separator 12, and may more preferably have an emitting surface 2 awhose center 2 b is so positioned as to face the corresponding sidesurface of the core 8, which is closer to the center of the separatorroll 10 than the ring portion (that is, the wound separator 12) is tothe center of the separator roll 10.

The above configuration causes an electromagnetic wave 4 having beenemitted from the center 2 b of the emitting surface 2 a to (i) travelthrough not the separator 12 but the core 8 of a separator roll 10 and(ii) strike the detecting surface 3 a of the sensor section 3. Thisprevents an emission line from showing in a captured image of aseparator 12.

X rays are emitted radially from the center 2 d of the focus 2 c as thecenter. An electromagnetic wave 4 travels through the wound separator 12in an oblique direction relative to the film surface of the separator 12and strikes the detecting surface 3 a of the sensor section 3. Thisprevents an emission line from showing in that portion of the capturedimage which corresponds to the image of the wound separator 12, and inturn prevents a false negative in defect detection without increasingthe number of image-capturing operations.

In terms of prevention of an emission line, the radiation source section2 may preferably have a focus 2 c so positioned as not to face thatportion of the corresponding side surface of a separator roll 10 held bythe holding mechanism 20 which is not the wound separator 12, and maymore preferably have a focus 2 c so positioned as to face thecorresponding side surface of the core 8, which is closer to the centerof the separator roll 10 than the ring portion (that is, the woundseparator 12) is to the center of the separator roll 10. This morereliably prevents an emission line from showing in a captured image of aseparator 12.

The defect inspection device 1 is configured such that no structure ispresent, and only air is present, between the radiation source section 2and a separator roll 10 held by the holding mechanism 20 and between aseparator roll 10 held by the holding mechanism 20 and the detectingsurface 3 a of the sensor section 3.

The defect inspection device 1, which is configured as above, is capableof creating a clear captured image of a separator roll 10 as compared toa case in which a structure is present between a separator roll and alight-receiving surface of a sensor section. The defect inspectiondevice 1 is thus capable of accurately inspecting a separator roll 10for a defect inside the separator roll 10.

The defect inspection device 1 is, as an example, configured such that(i) the forward end of the holding mechanism 20, which extends in theX-axis direction, is inserted in the central hole 8 a of the core of aseparator roll 10 so that the holding mechanism 20 holds a centralportion of the separator roll 10 and that (ii) the radiation sourcesection 2 and the sensor section 3 face each other with the separatorroll 10 therebetween.

The above configuration allows only a separator roll as an inspectiontarget to be present between the radiation source section 2 and thesensor section 3. This prevents something other than a separator roll 10from showing in a captured image, thereby making it possible to create acaptured image that facilitates defect inspection.

When the defect inspection device 1 is used to inspect a separator roll10 for a defect inside the separator roll 10, the defect inspectiondevice 1 may preferably be in a clean environment, for instance, beplaced in a clean room. The clean environment may preferably have aclass of, for example, not more than 100,000. Carrying out defectinspection in such an environment makes it possible to reduce the riskof a foreign object adhering to the separator roll 10 during or afterthe inspection. Further, the space surrounded by a wall containing, forexample, lead which space may be inside or outside the defect inspectiondevice 1 may preferably be also in a clean environment such as theabove. With this configuration, the defect inspection device 1 iscapable of accurately inspecting a separator 12, wound around a core,for a defect inside the separator 12.

Assuming as described above that the focus 2 c and the second surface A2of the separator roll 10 are separated from each other by a distance D1and that the focus 2 c and the detecting surface 3 a of the sensorsection 3 are separated from each other by a distance D2, the presentspecification defines D2/D1 as a measurement magnification.

The present invention has an object of creating a high-resolution X-rayimage of an inspection target over its entire region within a shorttime. The time length necessary to inspect a separator roll 10 is givenby the formula below. D2 needs to be set in such a manner as to minimizethe time length.(Exposure time period+Convey time)×Number of image-capturingoperations  (Formula 1)

With D2/D1 fixed, multiplying D1 (that is, the distance between thefocus 2 c and the separator roll 10) by X results in 1/(X²) as the doseper (time period·area) of the detecting surface 3 a. This indicates thatin a case where D1 is multiplied by X, receiving the same dose at thedetecting surface 3 a requires the exposure time period to beproportional to X². Thus, in terms of the exposure time period, D1 isadvantageously as small as possible. Decreasing D1, on the other hand,narrows the range over which the defect inspection device 1 is capableof capturing an image of a separator roll 10. This indicates that whiledecreasing D1 shortens the exposure time period, it increases (i) thenumber of image-capturing operations which number is necessary to coverthe entire region and (ii) the number of movements betweenimage-capturing operations, with the result of an increase of the timefor defect inspection.

Decreasing D2 increases the resolution of a captured image of aseparator roll 10 accordingly, but decreases the measurementmagnification. This requires the sensor section 3 to have a highresolving power, that is, a sensor section (FPD) having a small pixelsize. Increasing D2, on the other hand, reduces the constraint on thepixel size of the sensor section 3, but results in a larger sensorsection or a larger defect inspection device, with the result of anincrease in the space cost. Since an electromagnetic wave having awavelength within a range of 1 μm to 10 nm is emitted radially by aradiation source, the size of a foreign object (detection target) asprojected on the sensor section 3 is larger than the actual size of theforeign object. The pixel size of the sensor section 3 may be selectedin view of how many pixels are to be used to detect a foreign object(detection target). In a case where, for instance, three or more pixelsare to be used to detect a foreign object having a size of 100 μm, thepixel size may be selected with the lower limit being 100 μm÷3 (≈33 μm).

In view of the above matters, D1 may preferably be not less than 1.5times and not more than 4 times the width W, D2 may preferably be notless than 0.3 m and not more than 10 m, and D2/D1 may preferably be morethan 1 and not more than 40. The sensor section (FPD) may preferablyhave a pixel size of not less than 20 μm and not more than 2000 μm. Thisconfiguration makes it possible to (i) shorten the time length necessaryfor defect inspection of a separator roll 10 and (ii) carry out thedefect inspection accurately.

A single image-capturing operation may take a time period that isadjusted as appropriate on the basis of, for example, the time lengthnecessary to inspect a single separator roll 10, the sensitivity of thesensor section 3, and/or the number of products to be processed (thatis, the number of separator rolls 10 to be inspected) as long as thedefect inspection device 1 is capable of capturing an image of a defecthaving a size targeted for detection.

Depending on, for example, the time length necessary to inspect a singleseparator roll 10, the sensitivity of the sensor section 3, and/or thenumber of products to be processed (that is, the number of separatorrolls 10 to be inspected), the defect inspection device 1 may inspect aplurality of separator rolls 10 simultaneously by, for instance, (i)simultaneously capturing an image of a plurality of separator rolls 10that are placed on top of one another in the X direction or (ii)simultaneously capturing an image of a plurality of separator rolls 10arranged next to one another on the ZY plane.

(Method for Defect Inspection)

With reference to FIGS. 3 to 7, the description below deals with how thedefect inspection device 1 carries out defect inspection.

FIG. 4 is a diagram illustrating a captured image of a separator roll 10held by the holding mechanism 20. Although FIG. 4 illustrates a capturedimage of the entire separator roll 10, the defect inspection device 1may capture an image of (i) only a target region 3 b described later ofthe separator roll 10 or (ii) only a portion of the separator roll 10which portion includes a target region 3 b.

The sensor control section 33 sets a target region 3 b in a capturedimage of a separator roll 10 to actually determine whether the separatorroll 10 has any defect.

Depending on, for example, (i) the angle at which the electromagneticwave 4 enters a separator roll 10 and/or (ii) the length of the paththrough which the electromagnetic wave 4 has traveled from the emittingsurface 2 a of the radiation source section 2 to the detecting surface 3a of the sensor section 3, the captured image includes a region in whicha clear image is shown and a region in which an unclear image is shown.Using a region of a captured image in which region a clear image isshown makes it possible to reduce the number of false negatives indefect detection for accurate defect inspection.

In view of the above, the sensor control section 33 sets, as a targetregion 3 b, a region of a captured image in which region a clear imageis shown.

In a case where the defect inspection device 1 has captured an image ofa range and position identical to those of a target region 3 b, thedefect inspection device 1 may use the captured image as a target region3 b.

The present embodiment is configured such that the sensor controlsection 33 sets, as a target region 3 b, a quadrangular region includinga portion of the outer peripheral surface S2 of the core 8 and a portionof the outer peripheral surface S1 of the separator 12. In other words,the target region 3 b includes (i) a portion of the core 8 and (ii) aportion of the wound separator 12 over the full depth (the depth beingthe up-down direction of FIG. 4).

FIG. 3 shows a center line CE, which extends from the center 2 b of theemitting surface 2 a of the radiation source section 2 to the detectingsurface 3 a of the sensor section 3 in a direction perpendicular to thedetecting surface 3 a.

The target region 3 b has a dimension in the up-down direction whichdimension extends along the area of the sensor section 3 which area anelectromagnetic wave 4 a among other electromagnetic waves 4 strikesthrough a separator roll 10, the electromagnetic wave 4 a being emittedradially with an angle B1 relative to the center line CE which angle B1covers the outer peripheral surface S1 of the second side surface A2 ofthe separator roll 10.

The center line CE extends through the core 8 of the separator roll 10,the core 8 being closer to the center of the separator roll 10 than theseparator 12 is to the center of the separator roll 10.

When the sensor control section 33 has set a target region 3 b asillustrated in FIG. 4, the defect inspection device 1 captures an imageof the separator roll 10 set therein.

The capturing of an image means the following operation: The radiationsource section 2 emits an electromagnetic wave 4 in response to aninstruction from the radiation source control section 31. The sensorsection detects the electromagnetic wave 4 emitted by the radiationsource section 2 and having passed through the separator roll 10, andoutputs to the sensor control section 33 an electric signalcorresponding to the intensity of the electromagnetic wave 4 detected.The sensor control section 33 receives such electric signals from thesensor section 3, and generates a captured image based on those electricsignals.

Next, the sensor control section 33 extracts, from the captured imagegenerated, a first region R1, which corresponds to the target region 3b.

FIG. 4 shows in the first region R1 a foreign object 5 as a defect to bedetected. The foreign object 5 may be made of any of various materialssuch as metal and carbon. The foreign object 5 to be detected may haveany of various sizes. The foreign object 5 may be, as an example, 100 μmand have a thickness of approximately 50 μm. When the presentspecification specifies the size of a foreign object simply as, forexample, “100 μm” without specifying it as the thickness or width, thatdimension means the diameter of the circumscribed sphere of the foreignobject.

The foreign object 5 as a defect to be detected tends to, in a casewhere it has a large specific gravity, be detectable even if it issmall. Assuming that the defect to be detected is a metal foreignobject, in a case where a metal having a specific gravity ofapproximately 6 is detectable with a size down to, for example,approximately 100 μm under a certain inspection condition, a metalhaving a specific gravity of approximately 2 is detectable with a sizedown to approximately 300 μm. The defect inspection device 1 may beconfigured such that the size of a foreign object 5 as a detectiontarget is set as appropriate according to the kind (that is, specificgravity) of a metal foreign object as a detection target.

The defect inspection device 1 is capable of detecting a small foreignobject 5 in a case where the defect inspection device 1 has extended thetime for inspection by, for example, extending the exposure time periodand/or carrying out a plurality of image-capturing operations for thesame region of a separator roll 10. Thus, the relationship describedabove between the specific gravity of a metal foreign object as adetection target and its size assumes a fixed inspection time length.

As the respective specific gravities of typical metals, Fe hasapproximately 7.8, Al has approximately 2.7, Zn has approximately 7.1,stainless steel has approximately 7.7, Cu has approximately 8.5, andbrass has approximately 8.5. The metal material of a foreign object 5is, however, not limited to these examples.

FIG. 5 is a diagram illustrating the separator roll 10 of FIG. 4 as hasbeen rotated in the θ direction by a predetermined angle.

After the sensor control section 33 has extracted, from a capturedimage, a first region R1 (which corresponds to a target region 3 b), theholding mechanism control section 32 rotates the holding mechanism 20 inthe θ direction by a predetermined angle as illustrated in FIG. 5. Thiscauses the holding mechanism 20 and the separator roll 10 to (i) rotatein the θ direction by the predetermined angle and then (ii) stop. Thepresent specification uses the term “region R” to refer to a region thatthe sensor control section 33 extracts from each captured image and thatcorresponds to the target region 3 b.

The predetermined angle, by which the holding mechanism control section32 causes the holding mechanism 20 and a separator roll 10 to rotate inthe θ direction, refers to an angle not larger than the angle with which(i) no uncaptured region is present on the first side surface A1 of theseparator roll 10 when a plurality of regions R obtained by capturingimages of the separator roll 10 while causing the holding mechanism 20and the separator roll 10 to rotate by 360 degrees are so arranged as tooverlap with each other and (ii) the number of images captured is thesmallest.

The above configuration makes it possible to capture an image of theentire separator roll 10 efficiently. With the above configuration, theradiation source section 2 may preferably have an emitting surface 2 awhose center 2 b is so positioned as to face the sensor section 3. Withthis positioning, no uncaptured region being present on the first sidesurface A1 of a separator roll 10 means that no uncaptured region ispresent on the second side surface A2 as well. This makes it possible tocapture an image of the entire separator roll 10 more suitably.

When the holding mechanism control section 32 has caused the holdingmechanism 20 and the separator roll 10 to (i) rotate in the θ directionby a predetermined angle and then (ii) stop, the defect inspectiondevice 1 captures an image of the separator roll 10 as rotated.

Next, the sensor control section 33 extracts, from the captured imagegenerated, a second region R2, which corresponds to the target region 3b.

The second region R2 and the first region R1 as rotated overlap witheach other with no gap therebetween and are angled differently from eachother.

The operation is repeated of, as described above, (i) capturing animage, (ii) causing the separator roll 10 to rotate in the θ directionby a predetermined angle, and (iii) extracting a region after therotation which region corresponds to the target region 3 b.

FIG. 6 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 1 of the present invention.

FIG. 6 illustrates a defect inspection image including a first region R1through an eighteenth region R18, the defect inspection image being acombination of respective images of regions each of which corresponds tothe target region 3 b and is extracted from the entire circumference ofthe separator 12 having the shape of a ring. The separator 12 in theshape of a ring is shown in the combination of the first region R1through the eighteenth region R18 (all the regions R).

The first region R1 through the eighteenth region R18 (all the regionsR), which have been obtained by capturing images of the separator roll10 while causing the holding mechanism 20 and the separator roll 10 torotate by 360 degrees, have respective angles different from each otherby a predetermined angle, which is not larger than the angle with which(i) no uncaptured region is present on the first side surface A1 of theseparator roll 10 when the regions R adjacent to each other are soarranged as to overlap with each other and (ii) the number of imagescaptured is the smallest.

With the holding mechanism 20 rotating in the θ direction by apredetermined angle for each rotation as described above, the separatorroll 10 is moved relative to the radiation source section 2 in such amanner that an image is obtained of the entire separator 12 wound aroundthe core 8. This makes it possible to inspect the entire separator 12for a defect.

The defect inspection device 1 may alternatively be configured such thatthe separator roll 10 is moved relative to the radiation source section2 as the radiation source section 2 and the sensor section 3 are rotatedin the θ direction by a predetermined angle for each rotation with thecenter of the separator roll 10 as the rotation center (the holdingmechanism 20 is fixed).

The first region R1 through the eighteenth region R18 are arranged suchthat (i) no gap is present between adjacent regions and that (ii) thefirst region R1 through the eighteenth region R18 are angled differentlyfrom each other in such a manner that each overlapping portion has aminimum possible area.

The defect inspection device 1 is capable of generating a defectinspection image that combines images extracted of the entire separator12 having the shape of a ring as described above.

The present embodiment is configured to generate a defect inspectionimage of the entire ring-shaped separator 12 by carrying out, eighteentimes, the flow of (i) capturing an image, (ii) extracting a targetregion 3 b from the captured image, and (iii) causing the separator roll10 to rotate in the θ direction by a predetermined angle. The number ofthe repeated operations may be changed as appropriate.

The defect inspection device 1 may be configured to then cause thedefect inspection image to be displayed by a display (not shown in thedrawings). The defect inspection device 1 may also be configured to (i)for example, process the defect inspection image in order to determinewhether there is any defect to be detected and (ii) notify the operatorof the determination result.

As described above, the separator roll 10 is moved relative to theradiation source section 2, and the radiation source section 2 emits anelectromagnetic wave 4 to the separator roll 10 before and after therelative movement.

The radiation source section 2 thus emits an electromagnetic wave 4 to aregion of the separator roll 10 before the relative movement of theseparator roll 10 and to a region of the separator roll 10 which regionis different from the above region after the relative movement. Thisallows the sensor control section 33 to obtain a captured image of aregion of the separator roll 10 before the relative movement of theseparator roll 10 and a captured image of a region of the separator roll10 which region is different from the above region after the relativemovement.

The defect inspection device 1 may be configured such that the sensorsection 3 switches between detecting and not detecting anelectromagnetic wave 4, instead of the radiation source section 2switching between emitting and not emitting an electromagnetic wave 4,through the movement of the separator roll 10 relative to the radiationsource section 2. The defect inspection device 1 may, in other words, beconfigured such that while the radiation source section 2 constantlyemits an electromagnetic wave 4, the sensor section 3 switches betweendetecting and not detecting an electromagnetic wave 4. This allows thesensor control section 33 to obtain respective captured images ofdifferent regions R in a manner similar to the case in which theradiation source section 2 emits an electromagnetic wave 4fragmentarily. It is preferable that the sensor section 3 should switchbetween detecting and not detecting an electromagnetic wave 4 throughthe relative movement of the separator roll 10. Turning an X-ray sourceon and off frequently may cause a disadvantage such as emitted X raysbeing unstable and/or the X-ray source having a shorter life.

As described above, even in a case where the sensor section 3 has asmall detecting surface 3 a, the sensor control section 33 is capable ofobtaining a captured image of a wide area of a separator roll 10. Thisin turn makes it possible to inspect a wide area of a separator roll 10for a defect, and eliminates the need to spend a long time for defectinspection.

The radiation source section 2 emits an electromagnetic wave 4 to aseparator roll 10 before and after the separator roll 10 is movedrelative to the radiation source section 2. This configuration allowsthe sensor control section 33 to obtain a captured image of a separatorroll 10 at rest. This in turn ensures a long exposure time period unlikein a case where an image is captured of a separator roll being moved,and thereby makes it possible to obtain a bright and clear capturedimage. The above configuration thus makes it possible to carry outdefect inspection more accurately.

As described above, the defect inspection device 1 is capable ofcarrying out defect inspection accurately while preventing an increaseof the time necessary for the defect inspection.

The separator roll 10 is rotated relative to the radiation sourcesection 2 with the center of the separator roll 10 as the rotationcenter. The sensor control section 33 generates a captured image of sucha separator roll 10.

The sensor control section 33 combines a captured image generated beforethe relative movement of the separator roll 10 with a captured imagegenerated after the relative movement of the separator roll 10 in such amanner that the two images partially overlap with each other. Thisconfiguration makes it possible to create a captured image of a widearea of the separator roll 10 thoroughly. This in turn makes it possibleto efficiently create a captured image of a wide region of a separatorroll 10.

The sensor control section 33 may preferably cause captured images of aseparator roll 10 to partially overlap with each other in such a manneras to, while a separator roll 10 is rotated relative to the radiationsource section 2 with the center of the separator roll 10 as therotation center, generate captured images of such a separator roll 10and cause those captured images to partially overlap with each other.This configuration efficiently makes it possible to cause capturedimages to overlap with each other similarly.

The defect inspection device 1 may preferably be configured to obtain acaptured image that also shows a portion of the core 8. Thisconfiguration makes it possible to create a captured image of a widearea of the separator roll 10 thoroughly, the wide area including theinnermost portion (which is the closest to the core 8) of the separator12 of the separator roll 10.

The defect inspection device 1 may preferably be configured to obtain acaptured image that also shows a space outside the outer peripheralsurface S1. This configuration makes it possible to create a capturedimage of a wide area of the separator roll 10 thoroughly, the wide areaincluding the outermost portion (which corresponds to the outerperipheral surface S1) of the separator 12 of the separator roll 10.

The defect inspection device 1 uses the electromagnetic wave 4 as anelectromagnetic wave that the radiation source section 2 emits. Thisconfiguration makes it relatively easy to check whether there is anydefect inside a separator 12 wound around a core 8.

The defect inspection device 1 may be configured to capture a pluralityof images of the same region of a separator roll 10 while changing therespective relative positions of the radiation source section 2 and theseparator roll 10. Capturing a plurality of images (for example, twoimages) of the same region of a separator roll 10 while changing therespective angles of the radiation source section 2 and the separatorroll 10 makes it possible to, for example, (i) specify the position of aforeign object in the separator roll 10 (that is, the TD position in theseparator roll 10), (ii) specify the overall shape of a foreign objectin the separator roll 10, and/or (iii) detect a thin foreign object.

The defect inspection device 1 may be configured to, when capturing asecond image of the separator roll 10, capture an image of the entireseparator roll 10 again or alternatively capture an image of only anecessary region of the separator roll 10. For instance, after thedefect inspection device 1 captures an image of the entire separatorroll 10 by a method described above with reference to FIGS. 4 to 6 orany method described later for Embodiment 2 and its subsequentembodiments, the defect inspection device 1 may (i) specify, from thecaptured image, a region of the separator roll 10 in which region aforeign object is contained or something that looks like a foreignobject is shown and (ii) capture an image again of only that region ofthe separator roll 10.

In a case where a separator roll 10 contains a particularly small (thin)foreign object, capturing only one image of the separator roll 10 maynot be sufficient to find the foreign object. Thus, in a case where aforeign object as an inspection target is particularly small (thin), thedefect inspection device 1 may preferably capture a plurality of imagesof the entire separator roll 10 while changing the respective angles ofthe radiation source section 2 and the separator roll 10. This makes itpossible to detect a small (thin) foreign object.

The defect inspection device 1 is capable of, on the basis of, forexample, the time length necessary to inspect a single separator roll10, the sensitivity of the sensor section 3, and/or the number ofproducts to be processed (that is, the number of separator rolls 10 tobe inspected), being set to detect a foreign object 5 having a sizewithin a particular range.

For instance, setting the defect inspection device 1 to detect anyforeign object 5 that is not less than 100 μm and using the defectinspection device 1 for defect inspection of a separator roll 10 makesit possible to select, from among various separator rolls 10 that areproduced through a process of producing a separator roll 10 and that(possibly) contain foreign objects of various sizes, any separator roll10 that contains a foreign object 5 that is not less than 100 μm.

Removing, during the production process, any separator roll 10 in whichthe defect inspection device 1 has detected a foreign object 5 that isnot less than 100 μm makes it possible to select, from among variousseparator rolls 10 (possibly) contain foreign objects of various sizes,any separator roll 10 that contains only a small number of foreignobjects 5 which are not less than 100 μm or that is free from anyforeign object 5 which is not less than 100 μm.

Stated differently, including, in the process of producing a separatorroll 10, a defect inspection step involving the use of the defectinspection device 1 makes it possible to produce, from among variousseparator rolls 10 (possibly) containing foreign objects of varioussizes, a separator roll 10 that contains only a small number of foreignobjects 5 which are not less than 100 μm or that is free from anyforeign object 5 which is not less than 100 μm.

In particular, a separator roll 10 containing only a small number offoreign objects 5 that are not less than 100 μm has a low possibilitythat a foreign object 5 adhering to the separator 12 causes a failure.

Including, in the process of producing a separator roll 10, a defectinspection step involving the use of the defect inspection device 1 asdescribed above makes it possible to produce a separator roll that hasonly a small number of defects such as entry of a foreign object 5.

The defect inspection step may, as described above, preferably becarried out after the slitting step and before the packaging step duringthe process of producing a separator roll 10. This configuration makesit possible to efficiently inspect a separator roll 10 for any foreignobject 5 generated in the slitting step.

Including the defect inspection step in the process of producing aseparator roll 10 eliminates the need to inspect a separator 12 for anadhering foreign object 5 after the step of packaging the separator roll10, specifically during a production process of assembling a batterywith use of the separator 12 wound around the core 8.

The control section 30 may preferably be configured to, after an imageis captured of a separator roll 10 and before an image is captured ofanother separator roll 10 (that is, after the end of eachimage-capturing cycle), return each section moved for capturing an imageof the separator roll 10 (such as the holding mechanism 20) to itsinitial state. This prevents an inspection failure, a redundantinspection, and a malfunction such as starting an image-capturingoperation while the previous image-capturing operation has not finished.The control section 30 may preferably be configured to return eachsection to its initial state after the end of each image-capturing cycleas described above also for each defect inspection device describedlater of Embodiment 2 and its subsequent embodiments.

Modifications

FIG. 25 is a diagram illustrating the configuration of a defectinspection device 1L in accordance with a modification of Embodiment 1of the present invention.

FIG. 25 is a top view of a defect inspection device 1L in accordancewith a modification of Embodiment 1 of the present invention, the viewschematically illustrating the configuration of the defect inspectiondevice 1L. As illustrated in FIG. 25, the defect inspection device 1Lincludes a radiation source section 2, a sensor section 3, a controlsection 30L, a wall 47, a pre-inspection rack 201, a post-inspectionrack 202, and a robot arm (holding mechanism) 203. Since the robot arm203 doubles as a holding mechanism 20 (see FIG. 3), the defectinspection device 1L does not include a separate holding mechanism 20.

The wall 47 has a surface containing, for example, lead to prevent anelectromagnetic wave from passing therethrough easily so that theelectromagnetic wave used does not leak outward. The wall 47 is providedwith a door (not shown in FIG. 25), which is openable for a separatorroll 10 to be carried in and out.

The control section 30L differs from the control section 30 in that thecontrol section 30L includes a robot arm control section 32L in place ofthe holding mechanism control section 32 of control section 30. Thecontrol section 30L is otherwise similar in configuration to the controlsection 30. The robot arm control section 32L controls driving of therobot arm 203. The control section 30L may be positioned in the regionsurrounded by the wall 47 or outside that region.

The pre-inspection rack 201 is a member on which to place a separatorroll 10 that has not been subjected to defect inspection in the defectinspection device 1L. The pre-inspection rack 201 includes a holdingmember, which can be inserted in the central hole 8 a (see FIG. 2) ofthe core 8 from the side of the first side surface A1 of the separatorroll 10 to hold the separator roll 10. The post-inspection rack 202 is amember on which to place a separator roll 10 that has been subjected todefect inspection in the defect inspection device 1L. Thepost-inspection rack 202 includes a holding member, which can beinserted in the central hole 8 a (see FIG. 2) of the core 8 from theside of the first side surface A1 of the separator roll 10 to hold theseparator roll 10.

The defect inspection device 1L does not necessarily include apre-inspection rack 201 and a post-inspection rack 202 separately. Thedefect inspection device 1L may include a single rack that doubles as(i) a member on which to place a separator roll 10 that has not beensubjected to defect inspection and (ii) a member on which to place aseparator roll 10 that has been subjected to defect inspection. Forinstance, the single rack has two stages disposed on top of each other,and one of the upper and lower stages is used to place a separator roll10 that has not been subjected to defect inspection, whereas the otherof the upper and lower stages is used to place a separator roll 10 thathas been subjected to defect inspection.

The robot arm 203 is configured to, in response to an instruction fromthe robot arm control section 32L, move a separator roll 10 between thepre-inspection rack 201 and the post-inspection rack 202. The robot arm203 of the present embodiment doubles as a holding mechanism configuredto hold a separator roll 10 being inspected for a defect by the defectinspection device 1L.

The robot arm 203 includes a forward end 203 a configured to hold aseparator roll 10. The forward end 203 a is capable of (i) holding aseparator roll 10 without coming into contact with the separator 12 by,for example, holding the core 8 of the separator roll 10 and (ii)causing the separator roll 10 that the forward end 203 a is holding torotate by a predetermined angle for each rotation.

The robot arm 203 holds the core 8 of a separator roll 10 on thepre-inspection rack 201 from the side of the second side surface A2 ofthe separator roll 10 and moves the separator roll 10 from thepre-inspection rack 201. The robot arm 203 positions and holds theseparator roll 10, which has been moved from the pre-inspection rack201, between the radiation source section 2 and the sensor section 3 insuch an orientation that the first surface A1 faces the radiation sourcesection 2 and that the second surface A2 faces the sensor section 3. Therobot arm 203 is, at this stage, absent in that region of the separatorroll an image of which is to be captured. The defect inspection device1L then inspects the separator roll 10 for a defect as described abovewith reference to FIGS. 3 to 7.

After the defect inspection, the robot arm 203 moves the separator roll10 that the robot arm 203 is holding to the post-inspection rack 202.

The post-inspection rack 202 receives from the robot arm 203 theseparator roll 10 that has been inspected. Specifically, thepost-inspection rack 202 inserts its holding member (not shown in FIG.25) into the central hole 8 a (see FIG. 2) of the core 8 of theinspected separator roll from the side of the first side surface A1 ofthe separator roll 10 to receive the separator roll 10.

The robot arm 203, the pre-inspection rack 201, and the post-inspectionrack 202 move a separator roll 10 without coming into direct contactwith the separator 12 as described above.

The robot arm 203 not only receives a separator roll 10 from thepre-inspection rack 201 and hands it to the post-inspection rack 202,but also serves as a holding mechanism (as with the holding mechanism20) to hold a separator roll 10 being inspected for a defect.

The defect inspection device 1L may alternatively include two or moredefect inspection units, each defect inspection unit including aradiation source section 2, a sensor section 3, a robot arm 203, apre-inspection rack 201, and a post-inspection rack 202 all surroundedby the wall 47.

Embodiment 2

The description below deals with Embodiment 2 of the present inventionmainly with reference to FIGS. 6 and 7. Note that for convenience ofexplanation, identical reference numerals are given to members whichhave respective functions identical with those described in Embodiment1, and descriptions of the respective members are omitted.

FIG. 7 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 2 of the present invention.

In a case where as with the separator roll 10A illustrated in FIG. 7,(i) a separator roll includes a ring-shaped separator 12 having athickness larger than the thickness of a separator roll 10 (see FIG. 6),and (ii) the target region 3 b cannot cover the full depth (radialdirection) of the wound separator 12, the present embodiment captures aplurality of images of portions of the separator 12 which portions arenext to each other in the thickness direction (radial direction).

In this case, the present embodiment first captures images of a firstregion R1 through an eighteenth region R18 on the inner peripheral sideas illustrated in FIG. 6. The first region R1 through the eighteenthregion R18 (regions R) show the outer peripheral surface S2 of the core8 and have respective angles different from each other by apredetermined angle, which is not larger than the angle with which (i)no uncaptured region is present on the first side surface A1 of theseparator roll 10 when the regions R adjacent to each other are soarranged as to overlap with each other and (ii) the number of imagescaptured is the smallest.

Next, the holding mechanism control section 32 lowers the holdingmechanism 20, holding the separator roll 10, in the negative Z direction(that is, downward in FIG. 3) over a predetermined distance. Thepredetermined distance, by which the holding mechanism control section32 lowers the holding mechanism 20, is a distance that allows the targetregion 3 b to (i) include a portion of the outer peripheral surface S1of the separator 12 and (ii) overlap with any of the first region R1through the eighteenth region R18.

The present embodiment, by carrying out, nineteen times, the flow of (i)capturing an image of the separator roll 10, (ii) extracting a targetregion 3 b from the captured image, and (iii) causing the separator roll10 to rotate in the θ direction by a predetermined angle, capturesrespective images of a first region R21 through a nineteenth region R39on the outer peripheral side by a method similar to the method by whichthe present embodiment captures respective images of the first region R1through the eighteenth region R18 on the inner peripheral side.

The first region R21 through the nineteenth region R39 (regions R) showthe outer peripheral surface S1 of the separator 12 and have respectiveangles different from each other by a predetermined angle, which is notlarger than the angle with which (i) no uncaptured region is present onthe first side surface A1 of the separator roll 10 when the regions Radjacent to each other are so arranged as to overlap with each other and(ii) the number of images captured is the smallest.

The number of the repeated operations on the outer peripheral side isnot limited to 19, and may be changed as appropriate.

Embodiment 3

The description below deals with Embodiment 3 of the present inventionmainly with reference to FIGS. 8 and 9. Note that for convenience ofexplanation, identical reference numerals are given to members whichhave respective functions identical with those described in Embodiment 1or 2, and descriptions of the respective members are omitted.

FIG. 8 is a diagram schematically illustrating the configuration of adefect inspection device 1C in accordance with Embodiment 3 of thepresent invention.

The defect inspection device 1C includes a sensor section 3C, a holdingmechanism 20C, and a control section 30C in place of the sensor section3, the holding mechanism 20, and the control section 30 of the defectinspection device 1 (see FIG. 3).

The sensor section 3C is larger than the sensor section 3, and has adetecting surface 3Ca large enough to form an image of the entireseparator roll 10. The sensor section 3C may be configured to include aplurality of sensor sections 3.

The holding mechanism 20C is identical to the holding mechanism 20except that the holding mechanism 20C does not include a motor 22configured to rotate in the θ direction. The holding mechanism 20C doesnot cause a separator roll 10 that the holding mechanism 20C is holdingto rotate in the θ direction. This is because the holding mechanism 20Cdoes not need to move (for example, rotate) a separator roll 10 in orderto capture an image of the entire separator 12 of the separator roll 10,since the detecting surface 3Ca of the sensor section 3C is large enoughto form an image of the entire separator roll 10.

The holding mechanism 20C is capable of, in response to an instructionfrom the holding mechanism control section 32, moving in the X-axisdirection and the Z-axis direction. The holding mechanism 20C may beconfigured to be capable of moving also in the Y-axis direction, whichis perpendicular to the X-axis direction and the Z-axis direction.

The radiation source section 2 is so positioned as to have an emittingsurface 2 a with a center line CE coinciding with the central axis ofthe holding mechanism 20C. This configuration allows (i) anelectromagnetic wave 4 emitted by the radiation source section 2 tostrike the separator roll 10 uniformly and (ii) the electromagnetic wave4 having passed through the separator roll 10 to be detected by thesensor section 3C at the detecting surface 3Ca.

The sensor control section 33C is configured to generate a capturedimage of the entire separator roll 10 on the basis of electric signalsobtained by the sensor section 3C detecting electromagnetic waves 4.

FIG. 9 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 3 of the present invention.

As illustrated in FIG. 9, the sensor control section 33C is configuredto obtain a defect inspection image 3 bC, which is obtained by removingan unnecessary portion of the captured image which unnecessary portionis present around the region corresponding to the separator roll 10.

The defect inspection image 3 bC has a dimension in the up-downdirection which dimension, as illustrated in FIG. 8, extends in theup-down direction along a detecting surface 3Cb (that is, a portion ofthe detecting surface 3Ca of the sensor section 3C) which detectingsurface 3Cb an electromagnetic wave 4 a among other electromagneticwaves 4 strikes through a separator roll 10, the electromagnetic wave 4a being emitted radially with an angle B1C with the center line CE asthe center which angle B1C covers the outer peripheral surface S1 of thefirst side surface A1 of the separator roll 10.

Embodiment 4

The description below deals with Embodiment 4 of the present inventionmainly with reference to FIGS. 10 to 13. Note that for convenience ofexplanation, identical reference numerals are given to members whichhave respective functions identical with those described in any ofEmbodiments 1 to 3 and descriptions of the respective members areomitted.

FIG. 10 is a diagram schematically illustrating the configuration of adefect inspection device 1D in accordance with Embodiment 4 of thepresent invention.

The defect inspection device 1D differs from the defect inspectiondevice 1 in that the defect inspection device 1D includes a holdingmechanism 20D and a control section 30D in place of the holdingmechanism 20 and the control section 30 of the defect inspection device1 (see FIG. 3). The control section 30D differs from the control section30 in that the control section 30D includes a holding mechanism controlsection 32D in place of the holding mechanism control section 32 of thecontrol section 30. The defect inspection device 1D is otherwise similarin configuration to the defect inspection device 1.

The holding mechanism 20D is identical to the holding mechanism 20except that the holding mechanism 20D does not include a motor 22configured to rotate in the θ direction. The holding mechanism 20D doesnot cause a separator roll 10 that the holding mechanism 20D is holdingto rotate in the θ direction. The holding mechanism 20D is capable of,in response to an instruction from the holding mechanism control section32D, moving in the X-axis direction, the Z-axis direction, and theY-axis direction, which is perpendicular to the X-axis direction and theZ-axis direction. The holding mechanism 20D of the present embodiment isconfigured to move a separator roll 10 in the Z direction and the Ydirection without causing the separator roll 10 to rotate in the θdirection in order to move the separator roll 10 relative to theradiation source section 2.

FIG. 11 is a diagram illustrating a captured image of a separator roll10 held by the holding mechanism 20D. Although FIG. 11 illustrates acaptured image of the entire separator roll 10, the defect inspectiondevice 1D may capture an image of (i) only a target region 3 b of theseparator roll 10 or (ii) only a portion of the separator roll 10 whichportion includes a target region 3 b.

The sensor control section 33 sets, as a target region 3 b, aquadrangular region including a portion of the outer peripheral surfaceS2 of the core 8 and a portion of the outer peripheral surface S1 of theseparator 12. In other words, the target region 3 b includes (i) aportion of the core 8 and (ii) a portion of the wound separator 12 overthe full depth (the depth being the up-down direction of FIG. 11).

When the sensor control section 33 has set a target region 3 b, thedefect inspection device 1D captures an image of the separator roll 10set therein.

Next, the sensor control section 33 extracts, from the captured imagegenerated, a first region R41, which corresponds to the target region 3b.

FIG. 11 shows in the first region R41 a foreign object 5 as a defect tobe detected.

FIG. 12 is a diagram illustrating the separator roll 10 of FIG. 11 ashas been moved in the Y-axis direction and the Z-axis direction over apredetermined distance.

After the sensor control section 33 has extracted, from a capturedimage, a first region R41 (which corresponds to a target region 3 b),the holding mechanism control section 32D moves the holding mechanism20D in the Y-axis direction and the Z-axis direction over apredetermined distance as illustrated in FIG. 12. This causes theholding mechanism 20D and the separator roll to (i) move in the Y-axisdirection and the Z-axis direction over the predetermined distance andthen (ii) stop.

The predetermined distance, over which the holding mechanism controlsection 32D causes the holding mechanism 20D and a separator roll 10 tomove in the Y-axis direction and the Z-axis direction, refers to adistance not larger than the distance with which (i) no uncapturedregion is present on the first side surface A1 of the separator roll 10when a plurality of regions R obtained by capturing images of theseparator roll 10 while causing the holding mechanism 20 and theseparator roll 10 to, not rotate in the θ direction, but move in theY-axis direction and the Z-axis direction along the ring-shapedseparator 12 are so arranged as to overlap with each other and (ii) thenumber of images captured is the smallest. The present embodiment isconfigured such that each region R shows a portion of the outerperipheral surface S1 and a portion of the outer peripheral surface S2.This configuration makes it possible to capture an image of the entireseparator roll 10 efficiently.

When the holding mechanism control section 32D has caused the holdingmechanism 20D and the separator roll to (i) move in the Y-axis directionand the Z-axis direction over a predetermined distance and then (ii)stop, the defect inspection device 1D captures an image of the separatorroll 10 as moved.

Next, the sensor control section 33 extracts, from the captured imagegenerated, a second region R42, which corresponds to the target region 3b.

The second region R42 and the first region R41 as moved overlap witheach other with no gap therebetween and are parallel to each other.

The operation is repeated of, as described above, (i) capturing animage, (ii) causing the separator roll 10 to move in the Y-axisdirection and the Z-axis direction over a predetermined distance, and(iii) extracting a region after the movement which region corresponds tothe target region 3 b.

FIG. 13 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 4 of the present invention.

FIG. 13 illustrates a defect inspection image including a first regionR41 through a twenty-seventh region R68, the defect inspection imagebeing a combination of respective images of regions each of whichcorresponds to the target region 3 b and is extracted from the entirecircumference of the separator 12 having the shape of a ring. Theseparator 12 in the shape of a ring is shown in the combination of thefirst region R41 through the twenty-seventh region R68.

With the holding mechanism 20D moving in the Y-axis direction and theZ-axis direction over a predetermined distance for each movement asdescribed above, the separator roll 10 is moved relative to theradiation source section 2 in such a manner that an image is obtained ofthe entire separator 12 wound around the core 8. This makes it possibleto inspect the entire separator 12 for a defect.

The defect inspection device 1D may alternatively be configured suchthat the separator roll 10 is moved relative to the radiation sourcesection 2 as the radiation source section 2 is moved in the Y-axisdirection and the Z-axis direction over a predetermined distance foreach movement (the holding mechanism 20D is fixed).

The first region R41 through the twenty-seventh region R68 (each regionR), which have been obtained by capturing images of the separator roll10 while causing the holding mechanism 20 and the separator roll 10 to,not rotate in the θ direction, but move in the Y-axis direction and theZ-axis direction along the ring-shaped separator 12, have respectivepositions different from each other by a predetermined distance, whichis not larger than the distance with which (i) no uncaptured region ispresent on the first side surface A1 of the separator roll 10 when theregions R adjacent to each other are so arranged as to overlap with eachother and (ii) the number of images captured is the smallest.

The defect inspection device 1D is capable of generating a defectinspection image that combines images extracted of the entire separator12 having the shape of a ring as described above.

The present embodiment is configured to generate a defect inspectionimage of the entire ring-shaped separator by carrying out, twenty-seventimes, the flow of (i) capturing an image, (ii) extracting a targetregion 3 b from the captured image, and (iii) causing the separator roll10 to move in the Y-axis direction and the Z-axis direction over apredetermined distance. The number of the repeated operations may bechanged as appropriate.

The defect inspection device 1D may be configured to then cause thedefect inspection image to be displayed by a display (not shown in thedrawings). The defect inspection device 1D may also be configured to (i)for example, process the defect inspection image in order to determinewhether there is any defect to be detected and (ii) notify the operatorof the determination result.

Embodiment 5

The description below deals with Embodiment 5 of the present inventionmainly with reference to FIG. 16. Note that for convenience ofexplanation, identical reference numerals are given to members whichhave respective functions identical with those described in any ofEmbodiments 1 to 4 and descriptions of the respective members areomitted.

FIG. 16 is a diagram schematically illustrating the configuration of adefect inspection device 1E in accordance with Embodiment 5 of thepresent invention.

The defect inspection device 1E illustrated in FIG. 16 includes a rolldetecting section 40 and a roll detection control section 34 in additionto the members of the defect inspection device 1 (see FIG. 3).

The defect inspection device 1E includes a control section 30E, whichincludes the roll detection control section 34 in addition to themembers of the control section 30 (see FIG. 3).

The roll detecting section 40, in response to an instruction from theroll detection control section 34, detects the position of a separatorroll 10 in the defect inspection device 1E. The roll detecting section40 outputs to the roll detection control section 34 detectioninformation indicative of the position detected. The roll detectioncontrol section 34 determines on the basis of the detection informationfrom the roll detecting section 40 whether a separator roll 10 has beendisposed at a predetermined position in the defect inspection device 1E.The defect inspection device 1E may be configured to, for example, (i)cause a display (not shown in the drawings) to display the result of thedetection by the roll detection control section 34 or (ii) notify theoperator of the detection result with use of a sound or the like.

The above configuration prevents the defect inspection device 1E fromidling.

If a defect inspection device inspects a separator roll 10 for a defectwhile the separator roll 10 is out of position in the defect inspectiondevice, the separator roll 10 may have a region that was not inspected.The defect inspection device 1E prevents such a failure.

Further, if a defect inspection device inspects a separator roll 10 fora defect while the separator roll 10 is out of position in the defectinspection device, the separator roll 10 may come into contact with andbreak a movable part. The defect inspection device 1E prevents such afailure as well

Embodiment 6

The description below deals with Embodiment 6 of the present inventionmainly with reference to FIG. 17. Note that for convenience ofexplanation, identical reference numerals are given to members whichhave respective functions identical with those described in any ofEmbodiments 1 to 5 and descriptions of the respective members areomitted.

FIG. 17 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 6 of the present invention.The defect inspection device of the present embodiment is identical inconfiguration to the defect inspection device 1 of Embodiment 1 (seeFIG. 3).

A separator roll that is set in the defect inspection device 1 may havea small radius 10Fa, that is, may include a separator 12F wound around acore 8 which separator 12F has a thickness 12Fa much smaller than atarget region 3 b, as with the separator roll 10F illustrated in FIG.17.

In such a case, after the defect inspection device 1 has, in a firstimage-capturing operation, extracted a first region R71 corresponding toa target region 3 b, the holding mechanism 20 causes the separator roll10F to rotate in the θ direction by an angle θ1 larger than the angledescribed for Embodiment 1.

The angle θ1 is an angle that allows an intersection of a side R71 b, aside R72 a, and the outer peripheral surface S1 of a separator roll 10.The side R71 b is (i) one of the opposite sides R71 a and R71 b of thefirst region R71 that are parallel to the radial direction of theseparator roll and (ii) upstream of the side R71 a in the rotationdirection. The side R72 a is (i) one of the opposite sides R72 a and R72b of a second region R72, which corresponds to a target region 3 b ofwhich an image is to be captured next, that are parallel to the radialdirection of the separator roll 10 and (ii) downstream of the side R72 bin the rotation direction.

The above configuration reduces the number of image-capturing operationsnecessary.

The present embodiment may be configured such that (i) the thickness12Fa of the separator 12F of a separator roll 10F (that is, the outerdiameter of a separator roll 10F) is detected manually or automaticallyand that (ii) the rotation angle is adjusted to an appropriate angle(angle θ1) depending on the thickness 12Fa. In a case where the outerdiameter of a separator roll 10F is to be detected automatically, thesensor control section 33 may measure the outer diameter on the basis ofa captured image from the sensor section 3, or the defect inspectiondevice 1 may alternatively include a separate measuring mechanismconfigured to measure the outer dimensions of a separator roll 10F.

Embodiment 7

The description below deals with Embodiment 7 of the present inventionmainly with reference to FIG. 18. Note that for convenience ofexplanation, identical reference numerals are given to members whichhave respective functions identical with those described in any ofEmbodiments 1 to 6 and descriptions of the respective members areomitted.

FIG. 18 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 7 of the present invention.The defect inspection device of the present embodiment is identical inconfiguration to the defect inspection device 1 of Embodiment 1 (seeFIG. 3).

A separator roll that is set in the defect inspection device 1 may havea large radius 10Ga, that is, may include a separator 12G wound around acore 8 which separator 12G has a thickness 12Ga much larger than atarget region 3 b, as with the separator roll 10G illustrated in FIG.18.

In a case where the target region 3 b cannot cover the full depth(radial direction) of the wound separator 12G as described above, thepresent embodiment captures a plurality of images of portions of theseparator 12G which portions are next to each other in the thicknessdirection (radial direction).

FIG. 18 illustrates a separator 12G having a thickness 12Ga that can becovered by three target regions 3 b so arranged in the radial directionas to overlap with each other.

In this case, as described for Embodiment 1, the sensor control section33 first captures images of a first round of regions Rn1 (each region R)that show the outer peripheral surface S2 of the core 8 and that haverespective angles different from each other by a predetermined angle,which is not larger than the angle with which (i) no uncaptured regionis present on the first side surface A1 of the separator roll 10G whenthe regions R adjacent to each other are so arranged as to overlap witheach other and (ii) the number of images captured is the smallest.

Next, the holding mechanism control section 32 moves the separator roll10G in the Z direction, and the sensor control section 33 capturesimages of a second round of regions Rn2 (each region R) that show onlythe separator 12G and that have respective angles different from eachother by a predetermined angle, which is not larger than the angle withwhich (i) no uncaptured region is present on the first side surface A1of the separator roll 10G when the regions R adjacent to each other areso arranged as to overlap with each other and (ii) the number of imagescaptured is the smallest.

Next, the holding mechanism control section 32 moves the separator roll10G further in the Z direction, and the sensor control section 33captures images of a third round of regions Rn3 (each region R) thatshow the outer peripheral surface S1 of the separator 12G and that haverespective angles different from each other by a predetermined angle,which is not larger than the angle with which (i) no uncaptured regionis present on the first side surface A1 of the separator roll 10G whenthe regions R adjacent to each other are so arranged as to overlap witheach other and (ii) the number of images captured is the smallest.

The above configuration makes it possible to capture an image of theentire region of a separator 12G.

Embodiment 8

The description below deals with Embodiment 8 of the present inventionmainly with reference to FIGS. 19 to 21. Note that for convenience ofexplanation, identical reference numerals are given to members whichhave respective functions identical with those described in any ofEmbodiments 1 to 7 and descriptions of the respective members areomitted.

FIG. 19 is a diagram schematically illustrating the configuration of adefect inspection device 1H in accordance with Embodiment 8 of thepresent invention.

The defect inspection device 1H illustrated in FIG. 19 includes sensorsections 3H 1 and 3H2 and a control section 30H in place of the sensorsection 3 and the control section 30 of the defect inspection device 1(see FIG. 3). The control section 30H includes a sensor control section33H in place of the sensor control section 33 of the control section 30.The defect inspection device 1H is otherwise similar in configuration tothe defect inspection device 1.

The sensor control section 33H differs from the sensor control section33 in that the sensor control section 33H controls driving of each ofthe two sensor sections 3H 1 and 3H2.

The sensor sections 3H1 and 3H2 are disposed next to each other alongthe circumference of a separator roll 10, held by the holding mechanism20, relative to the rotation center of the separator roll 10.

FIG. 20 is a diagram illustrating a captured image of a separator roll10 held by the holding mechanism 20 of the present embodiment.

The sensor control section 33H sets a target region 3 b 1 for the sensorsection 3H1 and a target region 3 b 2 for the sensor section 3H2 asillustrated in FIG. 20. The defect inspection device 1H then captures animage of the separator roll 10 set therein. The sensor control section33H then extracts, from the captured image generated, (i) a region R101corresponding to the target region 3 b 1 and (ii) a region R102corresponding to the target region 3 b 2.

The holding mechanism 20 then causes the separator roll 10 to rotate inthe θ direction by a predetermined angle. During this step, the holdingmechanism 20 causes the separator roll 10 to rotate by an angle 1θ thatallows the region R102 to overlap with the target region 3 b 1 and thetarget region 3 b 2 by an equal area.

The angle 1θ is, stated differently, an angle by which to rotate aseparator roll 10 so that a region R based on the target region 3 b 2(which is one of the target regions 3 b 1 and 3 b 2 and which isupstream of the target region 3 b 1 in the rotation direction) willoverlap with the target regions 3 b 1 and 3 b 2 by an equal area.

Next, the defect inspection device 1H captures an image of the separatorroll 10 as has been rotated by the angle 1θ. The sensor control section33H then extracts, from the captured image generated, (i) a region R103corresponding to the target region 3 b 1 and (ii) a region R104corresponding to the target region 3 b 2.

FIG. 21 is a diagram illustrating the separator roll 10 of FIG. 20 ashas been rotated by an angle 30.

Next, the holding mechanism 20 causes the separator roll 10 to rotate byan angle 30 to minimize the number of image-capturing operationsnecessary. The angle 30 is three times larger than the angle 10. Thedefect inspection device 1H then captures an image of the separator roll10 as has been rotated by the angle 30. The sensor control section 33Hthen extracts, from the captured image generated, (i) a region R105corresponding to the target region 3 b 1 and (ii) a region R106corresponding to the target region 3 b 2. The region R105 overlaps withthe adjacent region R104.

The defect inspection device 1H is capable of, as described above,capturing an image of the wound separator 12 in its entirety of aseparator roll 10 while causing the separator roll 10 to rotatesequentially by the angles 10, 30, 10, 30, and so forth.

The defect inspection device 1H is capable of efficiently capturing animage of the entire separator 12 and of thereby efficiently inspectingthe separator 12 for a defect.

The number of sensor sections in the defect inspection device 1H is notlimited to two. The defect inspection device 1H may include three ormore sensor sections that are disposed next to each other along thecircumference of a separator roll 10, held by the holding mechanism 20,relative to the rotation center of the separator roll 10. Thisconfiguration further makes it possible to carry out defect inspectionefficiently.

Embodiment 9

The description below deals with Embodiment 9 of the present inventionmainly with reference to FIGS. 22 to 24. Note that for convenience ofexplanation, identical reference numerals are given to members whichhave respective functions identical with those described in any ofEmbodiments 1 to 8 and descriptions of the respective members areomitted.

FIG. 22 is a diagram illustrating the configuration of a defectinspection device 1J in accordance with Embodiment 9 of the presentinvention. The defect inspection device 1J illustrated in FIG. 22includes sensor sections 3J1 and 3J2 and a control section 30J in placeof the sensor section 3C and the control section 30C of the defectinspection device 1C (see FIG. 8). The control section 30J differ fromthe control section 30C in that the control section 30J includes asensor control section 33J in place of the sensor control section 33C ofthe control section 30C. The defect inspection device 1J is otherwisesimilar in configuration to the defect inspection device 1C. The sensorcontrol section 33J controls driving of the two sensor sections 3J1 and3J2.

The sensor sections 3J1 and 3J2 are disposed on top of each other, withthe sensor section 3J1 and the sensor section 3J2 positioned above andbelow the rotation center of a separator roll 10 held by the holdingmechanism 20J.

FIG. 24 is a diagram illustrating a defect inspection image of aseparator roll in accordance with Embodiment 9 of the present invention.

The sensor control section 33J sets a target region 3 b 1 for the sensorsection 3J1 and a target region 3 b 2 for the sensor section 3J2 asillustrated in FIG. 24. The defect inspection device 1J then captures animage of the separator roll 10 set therein. The sensor control section33J then extracts, from the captured image generated, (i) a region R101(region R) corresponding to the target region 3 b 1 and (ii) a regionR102 (region R) corresponding to the target region 3 b 2. Thisconfiguration makes it possible to capture images of two regions R inone image-capturing operation, and thus merely involves, not afull-circle rotation, but a half-circle rotation of a separator roll 10to capture an image of the entire separator 12. This in turn makes itpossible to carry out defect inspection efficiently.

FIG. 23 is a diagram illustrating the configuration of a defectinspection device 1K in accordance with a modification of Embodiment 9of the present invention. The defect inspection device 1K is identicalto the defect inspection device 1J except that the defect inspectiondevice 1K includes two radiation source sections.

The defect inspection device 1K includes radiation source sections 2K1and 2K2, sensor sections 3K1 and 3K2, and a control section 30K in placeof the radiation source section 2, the sensor sections 3J1 and 3J2, andthe control section 30J of the defect inspection device 1J.

The radiation source sections 2K1 and 2K2 have respective emittingsurfaces 2K1 a and 2K2 a, which correspond to the emitting surface 2 aof the radiation source section 2. The emitting surfaces 2K1 a and 2K2 ahave respective centers 2K1 b and 2K2 b, which correspond to the center2 b of the emitting surface 2 a. The radiation source sections 2K1 and2K2 have respective focuses 2K1 c and 2K2 c, which correspond to thefocus 2 c. The focuses 2K1 c and 2K2 c have respective centers 2K1 d and2K2 d, which correspond to the center 2 d of the focus 2 c. The sensorsections 3K1 and 3K2 correspond to the sensor sections 3J1 and 3J2. Thesensor control section 33K controls driving of the sensor sections 3K1and 3K2.

The defect inspection device 1K is configured such that the sensorsections 3K1 and 3K2 are disposed on top of each other, with the sensorsection 3K1 and the sensor section 3K2 positioned above and below therotation center of a separator roll 10 held by the holding mechanism 20and that the radiation source sections 2K1 and 2K2 are also disposed ontop of each other, with the radiation source section 2K1 and theradiation source section 2K2 positioned above and below the rotationcenter of a separator roll 10 held by the holding mechanism.

The defect inspection device 1K is capable of creating a captured imageillustrated in FIG. 24 as with the defect inspection device 1J.

The defect inspection device 1J (see FIG. 22) is capable of carrying outdefect inspection with use of a single radiation source section 2. Thedefect inspection device 1J, however, inspects the inside of a separatorroll for a defect with use of an electromagnetic wave 4 passing throughthe core 8, and tends to create a captured image with a low resolution.

The defect inspection device 1K (see FIG. 23), in contrast, uses tworadiation source sections 2K1 and 2K2 for defect inspection without anelectromagnetic wave 4 passing through the core 8. The defect inspectiondevice 1K needs to include a partition made of, for example, leadbetween the radiation source sections 2K1 and 2K2 to prevent theradiation source sections 2K1 and 2K2 disposed on top of each other frominterfering with each other. The defect inspection device 1K mayinclude, at a position adjacent to the respective emitting surfaces ofthe radiation source sections 2K1 and 2K2, a blocking plate for blockingan electromagnetic wave traveling in an unintended direction. This makesit possible to prevent the interference without greatly reducing theempty space inside the device.

The number of sensor sections in the defect inspection device 1K is notlimited to two. The defect inspection device 1K may include three ormore sensor sections that are disposed in point symmetry with therotation center of a separator roll 10 held by the holding mechanism 20.

[Recap]

A defect inspection device in accordance with a first aspect of thepresent invention includes: a holding mechanism configured to hold aseparator roll including (i) a core in a cylindrical shape and (ii) aseparator for use in a battery which separator is wound around the core;a radiation source section configured to emit an electromagnetic wave tothe separator roll, the electromagnetic wave being capable of passingthrough the separator roll; and a sensor section configured to detectthe electromagnetic wave having been emitted by the radiation sourcesection and passed through the separator roll.

With the above configuration, the radiation source section is configuredto emit an electromagnetic wave to the separator roll, theelectromagnetic wave being capable of passing through the separatorroll, and the sensor section is configured to detect the electromagneticwave having been emitted by the radiation source section and passedthrough the separator roll. This configuration makes it possible toinspect a separator roll for a defect such as a foreign object insidethe separator wound around the core.

The above configuration makes it possible to, after a separator roll hasbeen produced, inspect the separator roll for a defect inside theseparator wound around the core. This eliminates the need to prepare adefect inspection device for each of a plurality of sheet-shapedseparators produced by slitting an original sheet and each not havingbeen wound around a core. This in turn eliminates the need to prepare alarge number of defect inspection devices.

A defect inspection device in accordance with a second aspect of thepresent invention is configured as in the first aspect and maypreferably further include: a holding mechanism configured to hold theseparator roll.

With the above configuration, the radiation source section emits theelectromagnetic wave to a separator roll held by the holding mechanism,and the sensor section detects that electromagnetic wave. This ensures asufficient exposure time period as compared to a case in which an imageis captured of a separator being conveyed. This in turn makes itpossible to capture a clear image for accurate defect inspection.

A defect inspection device in accordance with a third aspect of thepresent invention is configured as in the first or second aspect and maypreferably be further configured such that no structure is presentbetween the separator roll and a detecting surface of the sensorsection.

The above configuration makes it possible to create a clear capturedimage of a separator roll as compared to a case in which a structure ispresent between the separator roll and a light-receiving surface of thesensor section. The defect inspection device is thus capable ofaccurately inspecting a separator roll for a defect inside the separatorwound around the core.

A defect inspection device in accordance with a fourth aspect of thepresent invention is configured as in any one of the first to thirdaspects and may preferably be further configured such that D2/D1 is morethan 1 and not more than 40, where D1 is a distance from an emittingsurface of the radiation source section to a second side surface of theseparator roll which second side surface is one of opposite sidesurfaces of the separator roll and which second side surface is on aside on which the sensor section is present, and D2 is a distance fromthe emitting surface of the radiation source section to a detectingsurface of the sensor section.

The above configuration makes it possible to (i) shorten the time lengthnecessary for defect inspection of a separator roll and (ii) carry outthe defect inspection accurately.

A defect inspection device in accordance with a fifth aspect of thepresent invention is configured as in any one of the first to fourthaspects and may preferably be further configured such that the radiationsource section is configured to emit the electromagnetic wave to theseparator roll from a side of a side surface of the separator roll.

The above configuration makes it possible to create a captured imagebased on an electromagnetic wave that has passed through, of the entireseparator roll, only the separator wound around the core. This in turnmakes it possible to create a clear captured image of, in particular,the inside of the separator wound around the core.

A defect inspection device in accordance with a sixth aspect of thepresent invention is configured as in any one of the first to fifthaspects and may preferably be further configured such that the radiationsource section is configured to emit the electromagnetic wave to theseparator roll in such a manner that the electromagnetic wave arrives atboth the separator and the core; and the sensor section is configured todetect the electromagnetic wave so as to capture an image that includesboth an image of the separator and an image of the core.

The above configuration makes it possible to create a captured image ofa wide area of the separator roll. This in turn makes it possible toreduce the number of image-capturing operations necessary and inspectthe entire separator roll thoroughly for a defect.

A defect inspection device in accordance with a seventh aspect of thepresent invention is configured as in any one of the first to sixthaspects and may preferably be further configured such that theelectromagnetic wave is an X ray. This configuration makes it relativelyeasy to check whether there is any defect inside the separator woundaround the core.

A defect inspection device in accordance with an eighth aspect of thepresent invention is configured as in the seventh aspect and maypreferably be further configured such that the radiation source sectionhas an emitting surface having a center that faces a portion of a sidesurface of the separator roll which portion does not correspond to theseparator.

A defect inspection device in accordance with a ninth aspect of thepresent invention is configured as in the seventh or eighth aspect andmay preferably be further configured such that the radiation sourcesection has an emitting surface having a center that faces a portion ofa side surface of the separator roll which portion corresponds to a sidesurface of the core. This configuration prevents an emission line fromshowing over an image of the separator in the captured image due to Xrays emitted from the center of the emitting surface. This in turnprevents a defect in the separator from becoming difficult to find as aresult of an emission line.

A defect inspection method in accordance with a tenth aspect of thepresent invention includes the steps of: causing a radiation sourcesection to emit an electromagnetic wave to a separator roll including(i) a core in a cylindrical shape and (ii) a separator for use in abattery which separator is wound around the core, the electromagneticwave being capable of passing through the separator roll; and detectingthe electromagnetic wave having passed through the separator roll.

The above configuration makes it possible to inspect a separator rollfor a defect such as a foreign object inside the separator wound aroundthe core. The above configuration also eliminates the need to prepare alarge number of defect inspection devices.

A method in accordance with an eleventh aspect of the present inventionfor producing a separator roll may preferably include the step of: (a)inspecting, by the defect inspection method according to the tenthaspect, a separator roll for a defect, the separator roll including (i)a core in a cylindrical shape and (ii) a separator for use in a batterywhich separator is wound around the core, the defect being presentinside the separator. This configuration makes it possible to produce aseparator roll including a separator wound around a core which separatorcontains only a small number of defects such as a foreign object.

A method in accordance with a twelfth aspect of the present inventionfor production a separator roll is configured as in the eleventh aspectand may preferably further include the steps of: (b) slitting anoriginal sheet so as to prepare the separator, the original sheet havinga width larger than a width of the separator; (c) winding the separator,prepared in the step (b), around the core so as to produce the separatorroll; and (d) packaging the separator roll, produced in the step (c),wherein the step (a) is carried out after the step (b) and before thestep (d).

The above configuration makes it possible to efficiently inspect, duringthe defect inspection step, a separator for any foreign object resultingfrom the slitting step, during which a foreign object tends to result.The above configuration also makes it possible to eliminate the need to,after a separator roll has been packaged, inspect the separator roll fora foreign object adhering to the separator.

A method in accordance with a thirteenth aspect of the present inventionfor production a separator roll is configured as in the eleventh ortwelfth aspect and may preferably be further configured such that thestep (a) is carried out in order to inspect the separator roll for aforeign object that is not less than 100 μm.

The above configuration makes it possible to produce a separator rollthat contains only a small number of foreign objects which are not lessthan 100 μm or that contains no such foreign object.

A separator roll in accordance with another aspect of the presentinvention may be produced by the method according to any one of thetenth to twelfth aspects. This configuration makes it possible toproduce a separator roll containing only a small number of defects suchas a foreign object.

A separator roll in accordance with a fourteenth aspect of the presentinvention includes: a core in a cylindrical shape; and a separator foruse in a battery which separator is wound around the core, the separatorroll containing, inside the separator, no foreign object that is notless than 100 μm. This configuration makes it possible to produce aseparator roll with a low possibility that a foreign object adhering tothe separator causes a failure.

The present invention is not limited to the embodiments, but can bealtered by a skilled person in the art within the scope of the claims.The present invention also encompasses, in its technical scope, anyembodiment derived by combining technical means disclosed in differingembodiments.

REFERENCE SIGNS LIST

-   -   1, 1C, 1D, 1E, 1H, 1J to 1L Defect inspection device    -   2 Radiation source section    -   2 a Emitting surface    -   2 b Center    -   3, 3C, 3H1, 3H2, 3J1, 3J2, 3 K1, 3K2 Sensor section    -   3 b, 3 b 1, 3 b 2 Target region    -   3 bC Defect inspection image    -   4, 4 a Electromagnetic wave    -   5 Foreign object    -   6 Slitting apparatus    -   8 Core    -   8 a Central hole    -   10, 10A, 10F, 10G Separator roll    -   12, 12F, 12G Separator    -   20, 20C, 20D Holding mechanism    -   30, 30C to 30E, 30H, 30J to 30L Control section    -   31 Radiation source control section    -   32, 32D Holding mechanism control section    -   33, 33C, 33H, 33J Sensor control section    -   203 Robot arm (holding mechanism)

The invention claimed is:
 1. A defect inspection device, comprising: aradiation source section having an emitting surface and configured toemit an electromagnetic wave to a separator roll including (i) a core ina cylindrical shape and having a central axis and (ii) a separator foruse in a battery which separator is wound around the core, theelectromagnetic wave being capable of passing through the separatorroll; a sensor section having a detecting surface and configured todetect the electromagnetic wave having been emitted by the radiationsource section and passed through the separator roll in order to inspectthe separator roll for a defect; and a holding mechanism configured tohold the separator roll such that the central axis of the core of theseparator roll is oriented parallel to a center line connecting a centerof the emitting surface of the radiation source section to the detectingsurface of the sensor section in a direction perpendicular to thedetecting surface.
 2. The defect inspection device according to claim 1,wherein the separator roll and the detecting surface of the sensorsection are not separated from each other by a structure.
 3. The defectinspection device according to claim 1, wherein D2/D1 is more than 1 andnot more than 40, where D1 is a distance from the emitting surface ofthe radiation source section to a second side surface of the separatorroll which second side surface is one of opposite side surfaces of theseparator roll and which second side surface faces the sensor section,and D2 is a distance from the emitting surface of the radiation sourcesection to the detecting surface of the sensor section.
 4. The defectinspection device according to claim 1, wherein the radiation sourcesection is configured to emit the electromagnetic wave to the separatorroll from a side of a side surface of the separator roll.
 5. The defectinspection device according to claim 1, wherein: the radiation sourcesection is configured to emit the electromagnetic wave to the separatorroll in such a manner that the electromagnetic wave arrives at both theseparator and the core; and the sensor section is configured to detectthe electromagnetic wave so as to capture an image that includes both animage of the separator and an image of the core.
 6. The defectinspection device according to claim 1, wherein the electromagnetic waveis an X ray.
 7. The defect inspection device according to claim 6,wherein the center of the emitting surface of the radiation sourcesection faces a portion of a side surface of the separator roll whichportion does not correspond to the separator.
 8. The defect inspectiondevice according to claim 6, wherein the center of the emitting surfaceof the radiation source section faces a portion of a side surface of theseparator roll which portion corresponds to a side surface of the core.9. A defect inspection method, comprising the steps of: causing aradiation source section having an emitting surface to emit anelectromagnetic wave to a separator roll including (i) a core in acylindrical shape and having a central axis and (ii) a separator for usein a battery which separator is wound around the core, theelectromagnetic wave being capable of passing through the separatorroll; and detecting, by a sensor section having a detecting surface, theelectromagnetic wave having passed through the separator roll in orderto inspect the separator roll for a defect, wherein the central axis ofthe core of the separator roll is oriented parallel to a center lineconnecting a center of the emitting surface of the radiation sourcesection to the detecting surface of the sensor section in a directionperpendicular to the detecting surface.
 10. A method for producing aseparator roll, the method comprising the step of: (a) inspecting, bythe defect inspection method according to claim 9, a separator roll fora defect, the separator roll including (i) a core in a cylindrical shapeand (ii) a separator for use in a battery which separator is woundaround the core, the defect being present inside the separator.
 11. Themethod according to claim 10, further comprising the steps of: (b)slitting an original sheet so as to prepare the separator, the originalsheet having a width larger than a width of the separator; (c) windingthe separator, prepared in the step (b), around the core so as toproduce the separator roll; and (d) packaging the separator roll,produced in the step (c), wherein the step (a) is carried out after thestep (b) and before the step (d).
 12. The method according to claim 10,wherein the step (a) is carried out in order to inspect the separatorroll for a foreign object that is not less than 100 μm.